Rotary motors are utilized in a wide number of devices. One such device is the common ceiling fan. Generally, a ceiling fan motor drives a number of radially extending fan blades that propel or impel air within a room. The fans arms are attached to the rotary motor at a ceiling fan rotor plate which is coupled to the output shaft of the motor. Each fan arm is secured to the rotor plate with a fan arm bracket having two apertures. The rotor plate contains a number of radial holes drilled in closely spaced pairs which serve as mounting points for the blades. Each pair includes a first and second hole positioned at a selected distance from the center of the rotor plate. If the fan motor is designed for four fan arms, four pairs of holes are drilled at an equal distance from the center of the shaft. The radius of the first hole in each pair is offset 90.degree. from the radii of the first holes of the adjacent pairs. Similarly, the radius of the second hole of each pair is offset 90.degree. from the second holes of the adjacent pairs. Essentially, the first holes of each pair and the second holes of each pair are angularly equidistant from the corresponding first and second holes of the other pairs. If the fan motor is designed for five arms, five pairs of holes are drilled in the rotor plate so that the angle between the radius of first and second holes and the radii of the corresponding first and second holes of the adjacent pairs is 72.degree.. Similarly, if the ceiling fan is designed for three fan blades, the first and second holes of each pair are positioned at 120.degree. angles from the corresponding first and second holes of the adjacent pairs. To assemble the fan blades to the motor, the apertures of the fan arm brackets are aligned with the pairs of radial holes and are attached by screws received within the rotor plate.
The placement of the radial holes in the rotor plate provides an effective and simple means for attaching fan blades to the ceiling fan motor. However, the varying configurations of radial holes are not easily adaptable for mounting accessories otherwise suitable for use with all types of ceiling fan motors. For instance, pending U.S. patent application Ser. No. 08/953,598, filed Oct. 17, 1997, which is hereby incorporated in its entirety by reference, discloses an air filter accessory that may be driven by a wide variety of ceiling fan motors. However, the placement of the attachment apertures on the air filter accessory is dictated by the number and configuration of radial holes in the rotor plate of the fan motor. Thus, a different model of air filter accessory might be required for each different model of ceiling fan rotor plate. Producing a number of different models would result in a number of unnecessary inefficiencies. If a separate accessory is needed for each different ceiling fan motor, the cost of production of the accessories is increased, maintaining inventory becomes more difficult, and purchasers are required to select the model of air filter accessory that matches their existing ceiling fan motor. Thus, a universal mounting adaptor is needed to mount accessories to rotary motors and, particularly, to ceiling fan motors having different patterns of radial holes.